The Kansas City Chiefs have lost another key piece along their depth-challenged offensive line.

The team on Friday announced that starting right tackle Donald Stephenson has been suspended by the NFL for the first four games of the regular season. NFL Media Insider Ian Rapoport reported that the third-year blocker was banned for violating the league's policy on performance enhancing substances.

"Obviously losing Donald is disappointing, but we are in full compliance with the league's policy," the team wrote on the its official website. "We will have no further comment on the situation."